1-2 Introduction and Theory of Operation 5707070-A
Advanced Energy
®
Components of the Sono-Trak™ Doppler Ultrasonic Flow
Meter System
A typical Doppler flow meter system is comprised of an electronics enclosure (with a
display panel), a digitizer, and two clamp-on transducers.
ELECTRONICS ENCLOSURE AND DISPLAY PANEL
The display panel in the electronics enclosure features an easy-to-read LCD screen, a
keypad, and LEDs to interface with the flow meter. The Doppler flow meter can be
wall mounted for permanent installation or a portable option is also available.
TRANSDUCERS AND CABLING
The Doppler flow meter is configured with clamp-on transducers. When installed, the
transducers sense fluid flow through a pipe and send this information to the system
electronics. The electronics then convert, transmit, and display the received data.
The clamp-on transducers allow you to install the Doppler flow meter without
shutting down flow and are ideal for smooth, clean pipe walls. The transducers and the
digitizer are NEMA 6-rated and fully submersible. However, for continuous
submersion, the transducers and the digitizer need to be specially encapsulated to
prevent corrosion. Contact “EMCO Flow Systems Support” on page 3-11 for
information on configuring your meter for continuous submersion.
The standard cable length between the electronics enclosure and the transducers is 25
feet. Custom cable lengths up to 5000 feet are available. See “EMCO Flow Systems
Support” on page 3-11 for contact and ordering information.
THEORY OF OPERATION
The Sono-Trak™ Doppler ultrasonic flow meter measures flow velocity by sensing
signals from reflective materials within a liquid and measuring the frequency shift due
to the motion of these reflective materials. The Doppler effect states that the received
frequency is a function of the transmitted frequency and the relative motion between
transmitter and the receiver.
The classic example of the Doppler effect is the train whistle increasing in pitch to the
listener at the station as the train approaches, then decreasing in pitch as the train
moves away from the station. To the person riding on the train, the pitch remains the
same. The increasing pitch is due to phase-front compression and the decreasing pitch
is due to phase-front expansion. The Doppler flow meter uses this effect to measure
the velocity of a liquid through a pipe wall.
